The present invention relates to techniques for formation of shaped structures on a semiconductor substrate. More particularly, one application of such shaped structures is to form structures which alter some aspect of an electromagnetic beam produced by the semiconductor. One example is a semiconductor lens.
Much interest has been recently placed on formation of optical structures using semiconductors. Semiconductor light emitting diodes ("LEDs") and vertical cavity surface emitting devices ("VCSELs") are known. These devices produce electromagnetic radiation, e.g., Infra Red ("IR") radiation, or light, from a semiconductor device.
The light produced by the semiconductor device must be coupled from the semiconductor device into a light channeling element, as air or a light channeling fiber. However, the actual coupling of the light can cause internal reflection at the interface between the semiconductor light emitting device and the medium such as air. In certain cases, the light can be totally internally reflected, resulting in very low coupling efficiency.
It is known to use a lensing element as part of a semiconductor. For example, U.S. Pat. No. 5,023,447 explains that it is desirable to use a semispherical lens in a semiconductor. However, the lens is separately formed and glued into place.
The present disclosure describes formation and use of a optical property altering device, e.g., a lens, out of a portion of the semiconductor substrate.
For example, the device as described herein forms a hemispherical cap at the top surface. This hemispherical cap acts as a lens to alter the optical characteristics.